Roof and wall construction for open-hearth furnaces



Oct. 2, 1928.

F. H. LOFTUS ROOF AND WALL CONSTRUCTION FOR OPEN HEARTH FURNACES Filed ay 24. 1927 5 Sheets-Sheet Oct, 29 1928.

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l F.H.LoFTus ROOF AND WALL CONSTRUCTION FOR OPEN HEARTH FURNACES Filed Mayv24, 1927 3 Sheets-Sheet 5 FIS INVENTOR Fred H. LOTUS bwmzwwm his aftfofney lmaterial causing a sweating or fluxing ac- .Patente'd Oct. 2, 1928.

UNITED lsra/.1155

-1,686,387 PATENT OFFICE., y

FRED H. LOF'JJU'S, 0F PITTSBURGH, PENNSYLVANIA.

Roon AND WALL CONSTRUCTION ron OPEN-HEARTH FURNACJES.l

Application mea- May 24,

Thisinvention relates to a wall and roof construction for furnaces, and more especially to one for use in basic open hearth backs along the front and back walls and over the hearth of the furnace, which lis subject to rapid destruction due to the operation of the furnace.

The destructionis caused by abrasion and chemical reaction. During the initial stage of the heat, when the furnace is charged with lime and scrap, the scrap fills the laboratory of the furnace almost to the roof, leaving a channel between the scrap and the back wall and also a channel between the scrap and the front wall. The scrap causes the flameto divide, so that a portionv of it passes along the back wall and the remainder along the front wall. The flame thus comes in contact with a section of the brick work, and in contact with the upper portion of the Walls, causing this area to become highly heated and to constitute a zone of destruction for both the walls and the roof. The gases, during this initial stage of the heat, abrade the brick work of the roof and walls in these-regions until the' scrap charge becomes melted. After the iron has been charged, and the lime begins to rise the gases become laden with basic oXides. uring this operation, the furnace has been constantly gaining in temperature,- and the portions of'both the walls and roof along the skew-backs are at a high temperature. Due to the high temperature in the regions noted, the basic oxides react with the acid tion. l

In such prior construction 'the front and back walls of a basic open hearth furnace require frequent repairs and, replacement; the usualcampaign of the back wall of a 1927. Serial N0. 193,784.

furnace being ,approximately seventy-five heats, and the usual campaign of the front Wall approximately one `hundred heats.

The maintenance of walls has been given a great deal of consideration, and efforts have been made to provide a construction in which the diiculties caused by erosion are overcome. Operators have found that by extending the banking material upwardly oon the walls to the level of 'the skew-back channels, they are able to protect the walls ofthe furnace. lSuch is the practice in tilting furnaces, and the same results have been attained in stationary furnaces by an outward extension of the furnace walls .with

consequent. changes Vin the construction.' of the frame work of the furnace;

In the present invention there is provided a construction in which the walls maybe covered with banking material, without .the

' necessity of any alteration in the width of the furnace or increase in the width of the furnace roof. l

In the present invention the'usua'l roof construction, in which a uniformly curved roof is supported on the skew-backs, is replaced by a special wall and roof structure. This structure comprises a uniformly curved lcentral roof portion, supported by auxiliary skews, and intermediate portions which spring from abbreviated front and back walls. These intermediate portions meet the roofsection at a lpoint inwardly of the furnacelaboratory, which is removed vertically from the skew-backs a sufficient distance to permit this section to take the place of the deleted portionv of the furnace wall. In order to secure this effect the segments arising from the front and back walls are .formed on thearc of a circle having a much brick, or `other suitable material 'which is non-reactive to the l.basic laden fumes in the furnace, so that they are capable of resisting lthe chemical and abrasive action of the gases therein. For this reason these roof and Wall ,segments permit a` reduction inl both the height and thickness of the furnace walls,

and provide proper conditions lfor utilizing bottom material to'cover the face of the walls. The form and arrangement of the `roof and wall segments is such that their use the -cubical'contents'of the-laboratory of the furnace. Whereas the use of auxiliary skews and chrome brick segmentsisodisclosed and claimed inco-p'ending application Serial No. 181,062, filed April 5, 1927, such application does not disclose a form and arrangement of the non-reactive segments whichpermits these segments to replace a relatively great vertical extent of the front or back walls of the furnace.

In the accompanying drawings Figure 1 is a vertical transverse section through a furnace embodying the improvements of the present invention,'and showing the back walll of the furnace provided with my wall reducing segment; Figure 2 is a similar view, but showing both the front andback walls provided with segments of the same form and arrangement; and Figure 3 is a vertical sectional view taken on the line 3--3 of Figure 2. I Y

In the drawings, and with reference particularly to Figure 1 thereof, the reference numeral l designates the .hearth of thev furnace, and thereference numeral 2 the bucks a-ys of the furnace frame. Opposite buckstays are interconnected by tierods 3. Extending vertically from the hearth 1 of the furnace isthe abbreviated back wall 4 and the front wall 5.-. On front wall' 5 is the skew-back 6, which is supported by a channel f member 7. Y

The roof, designated generally by the reference numeral 8, comprises the central or roof portion proper 9 formed of silica brick on a continuous curve. Adjacent the front and back walls of the furnace, are segments or portions 10 and 10a of a material which is non-reactive to the basic oxides which impinge against these portions of the roof, in what has been herein called the zones of destruction. Such material is desirably chrome brick, but may be magnesite brick, or other suitable refractory material which is non-reactive under the conditions of operation in the furnace. Because of thein- ,ability of chrome or magnesite brick to withw dicated generally by the reference numeral 11, which are interposed between the central or. roof portion proper 9 and the outer nonreactivev portions 10 and 10.. The thrust members 11 comprise metallic side members 12 and 13,` whieh are interconnected by means of brackets 14." When assembled in a furnacel roof, as shown in Figure 3, the bracket members 14 are desirably so positioned as to i straddle and interconnect adjacent lengths of the side members 12 and 13. Between side members 12 and 13 are interposed al succession of blocks 15,v which may,

be of silica brick or other suitable refractory material, As shown in Figures 1 and 2, the' blocks 15 are so formed as to have an outconformation of the blocks permits them to be securely held in position by the'side members 12 and 13, which are ,angular in section, as shown. In order that the blocks 15 may be inserted between the-side members, to ,be engaged thereby, the member 13 has a hinged connection 16 with thebrackets 14 to which it is attached. This side member may, therefore, be raised to permit the insertionv of the refractory block, andl may be lowered to engage'them after their insertion. A

The bracket 14 of the assembly is provided with lugs 17 vextending upwardly therefrom and having bolt holes for the reception of boltsJ 18 by which the bracket rod 20. Each of the supporting rods 20 4is connected with overhead beams 21 resting on crossbeams 22 which are supported by the buck-stays 2. The' supporting means the rods 20, as shown in Figure 3, comprise plates 23 extending over two of the beams 21, and a nut 24 which rests on the plate 23 and engages a screw threaded portion -on theupper end of the'rod 20. On one sideof the bracket 14 are spaced lugs 25 provided with bolt holes for receivingthe bolt 26 passingfthrough an eve 27 on a compression bar 28. At the other end of the compression bar is an eye 29 for receiving a bolt 3Q to connect rthe bar to one of the buck-stays 2.

-When in position in the furnace roof the thrust members 11 provide support for the roof, and, because of the thrust bar 28, serve to take the thrust of' the central or roof portion proper 9.

With reference to Figure 1 of the drawings, it will be noticed that the sideportion or segment 10 rests on the skew-back 6 on front wall 5, while the segment or portion luil 10 springs directly from the abbreviated back wall 4. The portion or segment 10 is so curved that it forms a uniform curve with the central or roof portion proper 9. The

wall and roof portion or 'segment 10% on the contrary, is formed on the arcof a circle of lesser radius than that on which the 'central roof portion proper 9 is formed. Its vertical extent is thus greater than that of the ,roof segment or portion 10, and its added vertical extent'serves to replace the poiion. deleted from .abbreviated back' wa 4.

Being composed of material which is vnonreactive to the 'furnace fumes, the segments 10 and 10a are also less subject to abrasion, because they are not .softened by chemical action at high temperatures. The may, therefore, be of a lesser thickness t an the central or roof portion proper 9. `Because of the material of which they are made they also do not break down into an viscous silicious material, as do the roof and walls of a basic open hearth furnace, when such roof and walls are made wholly of silica brick. As is well known, such viscous silicious material, when, present, flows down the walls of the furnace and so corrodes the same as togreatly reduce theirspan of use-mL ful service.

It will be observed that, owing to the alobreviation of back wall 4; the banking material'B, which in a basic open hearth furnace is composed of dolomite or some other calcareous material, or magnesite, may cover the entire vertical extent of the f back wall 4. This wall is therefore fully protected from the fumes within the furnace, s'o that the life of this portion of the furnace is indefinitely extended. As it is thus fully protected, it may also be made of a lesser. thickness than is usual for open hearth furnace walls. y

In Figure 2 of the drawings both the front wall 3l and back wall 32 of the furnace are abbreviated. The central or roof portion proper 33 is of uniform curvature and similar to the roofo portion proper 9' of Figure l. It is independently supported by similar auxiliary. skew-backs 34: In this modification, however, both the intermediate segment or portion 35 between the roof portion proper and back wall, and the intermediate segment or portion 36 between the c roof portion proper and the front wall, are

formed on the arc of a circle of lesser radius than that on which the roof portion proper is formed. In both instances therefore -these wall and roof portions meet. the roof portion proper at such vertical vpoint with .reference to theA abbreviated furnace walls that they serve to replace the deleted' portions of such walls. f'

Both the back and front walls of the furnace, as shown' in Figure may be completely covered by in the furnace. That is, the 'entire wall lies within the line formed by the angle of repose of the banking material when it is piled against the' sides of the furnace-in the furnace hearth.

A It should be particularly noticed that this effect is 'obtained without extending the upper endsv of the furnace walls upwardlyand.

outwardly. The present construction therefore avoids the expense andinconvenience incident to such wall'strctre.

What I claim is: fr; l. In Vfurnace construction the. {combinathe banking material B' Stion of an abbreviated wall, an independently supported roof section proper, and a. wall and roof portion of refractory mate'rial rising from the abbreviated wall and fnaoe and at such height that said wall and roof portion takes the place of the deleted portion of the abbreviated wall.

3. OIn furnace construction the combination of an abbreviated wall, an independently supported 'roof section proper, and a wall and roof portion of chemically neutral material hrising from the abbreviated wall and meeting the roof portion at a point in- ,90 wardly of the furnace and at such height that said Awall and roof portion takes the place ofthe deleted portion of the abbreviated wall.

4.- In furnace construction the combination of an abbreviatedu wall, an independent- 1y supported roof sectlon proper, and a wall and roof portion of' chrome brick rising from the abbreviated' wall and meeting the roof portion proper at a point inwardly of the furnace and at such height that said wall and roof portiony takes-the place of thedeleted portion of the abbreviated wall.

5. In furnace construction the combination of an abbreviated wall, an independently supported roofl section proper formed on a uniform curve, and a wall and vroofv portion of refractory material between the roof portion proper' and the'A abbreviated wall, said roof and wall 'portion being formed 110 on the arc of acircle of lesser radius than that on which the roof is formed.

6. In furnace. construction the combination of an abbreviated wall, an independently supported roof proper formed on a uniform curve, and a wall and roof portion of a material which is non-reactive to basic laden fumes between the roof portion proper and the abbvreviated'yvall, said roof and I wall portion being formed on thearc of a circle of lesser radius than that on which 4`the roof' is formed.

7. Iny .furnace construction the combination of fan abbreviated Wall, an independently supported roof section proper formed on a uni orm curve, anda wall and'roof portion of chemically neutral material between the roof portion proper and the ab-I breviated wall, said-roof and wall portion. being formed on the arc of a circleof lesser radius than that on which the roof is formed.

8. In furnace construction the combination of anv abbreviated wall, anL independently supported roof section proper formed on.

a uniform curve, and a wall and roof por- -tion o f chrome brick between the roof portion proper-and the abbreviated wall, said roof and wallportionbeing formed on the arc of a circle of lesser radius than that on which the roof is formed.

9; In furnace construction the combination of a furnace hearth, a furnace roof, a vertical wall so abbreviated as tolie wholly within a line formed by the angle of repose of banking materialin the hearth, and a structure of refractory material extending between the abbreviated furnace wall and thefurnace roof.

10; In furnaceconstructlon the combinationof a furnace hearth, a furnace roof, a

vvertical wall so abbreviated as to lie wholly within a line formed by the angleof repose of banking' material in the hearth, and a pesage? structure of refractory material' which is non-reactive to basic laden fumes extending between the abbreviated furnace wall and the furnace roof.

11.v In furnace construction thecombination of a furnace hearth, a furnace roof, a

structure of chemically neutral refractory material extending between the abbreviated furnace wall and the furnace roof.

12. In furnace construction the combination of a furnace hearth a furnace roof, a vertical wall so abbreviated as to lie wholly within a line formed by the angle of repose of vbanking material in the hearth, and a structurel of. chrome brick extending between the abbreviated furnace wall and the furnace roof. 5

In witness whereof, I C,

hand. v v

D FRED I-I. LOFTUS.

hereunto set my 

